When the car doesn’t feel right

November 28, 2012

Last week we explored the possible problems when something didn't sound right with your car. Now let's look at what might be wrong when something doesn't feel right.

Suppose you feel a:

- VIBRATION: While sitting still; it's probably a miss in the engine. f so it usually gets worse under acceleration, and may also be there at higher speeds. This means one or more cylinders are weak, usually caused by a faulty spark plug or plug wire, or possibly a fuel injector. It is never a fuel filter, so don't waste money by changing that, even if it was the first suggestion you got from a friend.

- VIBRATION: Driving slowly; but not when sitting still. It might be a belt separation in a tire, making it crooked. This would feel like a wobble from side to side at about 10 mph. It might continue to higher speeds, but the key here is that it happens going slowly.

- VIBRATION: Only at higher speed; usually means a tire is out of balance. This is most pronounced at 55 to 70 mph, and may not be evident at slower speeds. It is not an alignment problem so don't ask for one. Some tires are "out of round" and will vibrate the car even when they are in perfect balance. If a tire is wobbling at slow speeds, or out of round at high speeds, it should be replaced ASAP, BECAUSE IT IS FAILING AND WILL BLOW OUT. Pardon the shouting, but it's important.

- OCCASIONAL JERKING: Driving slow or fast; it is usually a misfire in the engine. This has various possible causes requiring professional diagnosis. Or it could be a nervous tic in the driver's foot. Also requires professional diagnosis.

- HESITATION: A brief delay when you step on the gas before the car actually goes. Gear heads like to call it "bogging down," or "not getting the gas." Neither description is being helpful or even accurate. Just call it a hesitation and get professional help. For the car, I mean, nothing personal. It will not be the fuel filter this time either, and it won't be "bad gas." That comes from tacos.

- SHUTS OFF WHILE DRIVING: And might restart after sitting a while. NOW you can suspect the fuel filter. It could, however, be a problem with the ignition. If changing the filter clears the problem, it means you guessed right. If it doesn't, you need professional help again. Intermittent ignition problems are very hard to diagnose and very expensive to guess at.

- SHAKING WHILE BRAKING: Not to be confused with the shake-and-bake cooking method. This is a pulsation, sometimes felt in the brake pedal or the steering wheel while braking. It is caused by warped rotors or drums. This requires a brake shop to resurface or replace the offending parts. It is caused by the heating and expansion of the cast iron parts that sometimes do not return to their original shapes. It is not uncommon. If the shaking is accompanied by a pulling and hot rubber smell it could be a stuck brake caliper, which can get the wheel so hot it could ignite the rubber tire. The caliper would have to be replaced along with any other heat-damaged parts.

- HARD STEERING: If equipped with power steering, the pump is not working. It is either low on fluid, or the belt is slipping or missing, or the pump is bad. It could be a sticking steering part, like a ball joint or tie rod, but that is rare. Sometimes it is caused by a faulty rack and pinion. If it only happens first thing in the mornings we call that "morning sickness," and it requires the replacement of the rack and pinion assembly. Don't worry; it's not really pregnant.

- PULLING: In either direction; meaning a constant pull or drift either left or right if you let go of the wheel. It is normal to drift downhill, following the slope or crown of the road, but on a flat road the car should go straight. It could be either a tire problem, or an alignment problem, or a brake problem. If switching the two front tires left to right reverses the direction of pull it proves that the tires are at fault. If the direction does not change it is an alignment problem, and professional help is needed. If the pull changes when you step on the brake it might be a dragging brake, either front or rear, and the offending brake will be much hotter than the other three after driving. If the tire ignites, it will probably total the car. Kids have toy cars called "hot wheels" that are lots of fun. The grownup version, not so much.